Pulse wave velocity (PWV) represents the velocity at which pressure pulses propagate through the arterial tree. PWV is considered as the gold standard measurement to assess arterial stiffness, and has been identified as an independent predictor of cardiovascular morbidity and mortality. In line with this data, in 2007 the European Society of Hypertension has introduced PWV as a recommended test to assess cardiovascular risk on its guidelines for the diagnosis and management of hypertension.
Nowadays techniques that allow assessing PWV non-invasively fall into two main categories. On the one hand, COMPLIOR (Colson, France), SphygmoCor (AtCor Medical, Australia), Vicorder (Skidmore Medical, UK) and PulsePen (Diatecne, Italy) rely on the placement of two pressure transducers onto two superficial arteries. These devices detect the arrival time of a pressure pulse that propagates through the arterial tree, and calculate the delay in pulse arrival times between the proximal and distal sensors. By approximately measuring the distance through which the pulse has propagated, one estimates then a pulse propagation velocity value. Large clinical studies support the reliability and clinical validity of this technique.
On the other hand, Arteriograph (TensioMed, Hungary) estimates aortic PWV by applying pulse wave analysis techniques to a pressure pulse recorded by an inflated brachial cuff. The major interest of this approach is that PWV measurements can be performed automatically, reducing the need of trained medical staff. The measurement is based on the fact that during systole, the blood volume having been ejected into the aorta generates a pressure pulse (early systolic peak). This pulse runs down and reflects from the bifurcation of the aorta, creating a second pulse (late systolic peak). The return time (RT S35) is the difference between the first and the second systolic pulse waves, and is claimed to be a surrogate of aortic PWV. Unfortunately, clinical and numerical studies currently question the reliability and working principles of the RT S35 technique.
A broader review on the technical and physiological background of the described techniques is provided in J. Solà, S. F. Rimoldi, and Y. Allemann, “Ambulatory monitoring of the cardiovascular system: the role of Pulse Wave Velocity”, in New Developments in Biomedical Engineering, Intech, 2010 (Ref. 1). Because COMPLIOR-like devices are the state of the art of non-invasive measurement of arterial stiffness, a new implemented technique that would reduce the need of trained medical staff is highly desired. This would have the advantage of being operator dependent, and thus would facilitate the introduction of PWV measurements in large scale ambulatory and follow-up studies.